Video and audio playback apparatus and video and audio playback method

ABSTRACT

A video and audio playback apparatus which generate a video and an audio at high-speed in accordance with the respective characteristics is provided. The apparatus plays back a video/audio data having a first video data encoded by an intra-frame encoding, a second video data encoded by an inter-frame prediction encoding and an audio data corresponding to the video frame of the first video data or the second video frame. The apparatus includes a deciding unit to determine a first rate, a second rate and a number of times; a first extraction unit to extract the first video data from the video/audio data at the first rate; a second extraction unit to extract the audio data from the video/audio data at the second rate; a playback unit to play back the first video data the number of times; and an audio playback unit to play back the audio data.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2009-5527, filed on Jan. 14, 2009, theentire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a video and audio playback apparatus and avideo and audio playback method.

DESCRIPTION OF THE BACKGROUND

In a video and audio recording apparatus, video and audio are digitized,encoded according to a standard such as MPEG, and recorded on arecording medium as digital data. The video and audio playback apparatusdecodes the digital data recorded on the recording medium and the playsback the video and the audio.

An art which plays back video and audio at a speed higher than a usualspeed is known in JP,P2004-140723A, for example. Skip playback givingcontinuity in some degree becomes possible by playing back predeterminednumber of frames normally in series after playing back a picture of oneframe for every several frames. However, an art which plays back thevideo and the audio in accordance with their characteristics is notshown in JP,2004-140723A.

SUMMARY OF THE INVENTION

An object of the invention is to provide an video and audio playbackapparatus and an video and audio playback method which plays back videoand audio in accordance with their respective characteristics athigh-speed playback.

A video and audio playback apparatus according to the one embodiment ofthe invention is a video and audio playback apparatus for playing back avideo and audio data having a first video data encoded by an intra-frameencoding, a second video data encoded by an inter-frame predictionencoding and an audio data corresponding to a video frame of the firstvideo data or the second video data. The apparatus includes: an inputunit configured to receive a playback speed; a deciding unit todetermine a first rate at which the first video data is extracted fromthe video and audio data, a second rate at which the audio data isextracted from the video and audio data, and a number of times which thefirst video data extracted is played back, in accordance with theplayback speed received by the input unit; a first extraction unitconfigured to extract the first video data from the video and audio dataat the first rate decided by the deciding unit; a second extraction unitconfigured to extract the audio data from the video and audio data atthe second rate decided by the deciding unit; a video playback unitconfigured to playback the first video data extracted by the firstextraction unit the number of times determined by the deciding unit; andan audio playback unit configured to playback the audio data extractedby the second extraction unit.

A video and audio data playback method according to the one embodimentof the invention is a video and audio data playback method for playing afirst video data encoded by an intra-frame encoding, a second video dataencoded by an inter-frame prediction encoding and an audio datacorresponding to a video frame of the first video data or the secondvideo frame. The method includes: a receiving step to receive a playbackspeed, a deciding step to decide a first rate at which the first videodata is extracted from the video and audio data, a second rate at whichthe audio data is extracted from the video and audio data, and a numberof times which the first video data extracted is played back, inaccordance with the playback speed received by the receiving step; afirst extracting step to extract the first video data from the video andaudio data at the first rate decided by the deciding step; a secondextracting step to extract the audio data from the video and audio dataat the second rate decided by the deciding step; a first playing backstep to play back the first video data extracted by the first extractingstep the number of times determined by the deciding step; and a secondplaying back step to play back the audio data extracted by the secondextracting step.

A video and audio playback apparatus according to the one embodiment ofthe invention includes: a recording medium configured to record a videodata having a plurality of video frames including a first video dataencoded by an intra-frame encoding and a second video data encoded by aninter-frame prediction encoding, and an audio data having an audio framedata corresponding to the video frames; a storage unit configured torecord a video frame extraction rate at which the first video frame datais extracted from the video data, an audio frame extraction rate atwhich the audio frame data is extracted from the audio data, and anumber of times of a video playback which the first video frame dataextracted is played back, according to a playback speed; an input unitconfigured to receive the playback speed; a deciding unit configured toread the video frame extraction rate, the audio frame extraction rate,and the number of times of the video playback, in accordance with theplayback speed received by the input unit with reference to the storagemedium, and to decide a first rate at which the first video frame datais extracted from the video, a second rate at which the audio frame datais extracted from the audio data, and the number of times which thefirst video data extracted is played back; a medium control unitconfigured to read the video data and the audio data from the recordingmedium in accordance with the playback speed received by the input unit;a first extraction unit configured to extract the first video frame dataat the first rate from the video data; a second extraction unitconfigured to extract the audio frame data at the second rate from theaudio data; a video playback unit configured to play back the number oftimes the first video frame data extracted by the first extractionunits; and an audio playback unit configured to play back the audioframe data extracted by the second extraction unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a video and audio recording andplayback apparatus 10 according to a first embodiment of the presentinvention;

FIG. 2 is a schematic diagram showing an example of extraction andplayback condition table T; and

FIG. 3 is a flow chart showing an example of operating procedure of thevideo and audio recording and playback apparatus 10, and

FIG. 4 is a block diagram showing a video and audio recording andplayback apparatus 10 according to a modification of the firstembodiment.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the invention will be explained in detailwith reference to the drawings. FIG. 1 is a block diagram showing avideo and audio recording and playback apparatus 10 of one embodiment ofthe present invention. The video and audio recording and playbackapparatus 10 is capable of recording and playing back of video andaudio, and is capable of adjusting a playback speed of the video and theaudio suitably.

The video and audio recording and playback apparatus 10 includes a videoinput unit 111 a, an audio input unit 111 b, an encoding unit 112, amedium control unit 113, a recording medium 114, an video extractionunit 122 a, an audio extraction unit 122 b, a video decoding unit 123 a,an audio decoding unit 123 b, a video output unit 124 a, an audio outputunit 124 b, a main control unit 131, a storage unit 132, and anoperation input unit 133.

The video input unit 111 a is a device which converts an image into anelectrical signal, and the video input unit 111 a is a televisioncamera, for example. The video input unit 111 a outputs a video signalto the encoding unit 112.

The audio input unit 111 b is a device which converts sound into anelectrical signal, and the audio input unit 111 b is a microphone, forexample. The audio input unit 111 b outputs an audio signal to theencoding unit 112.

The encoding unit 112 encodes the video signal which is outputted fromthe video input unit 111 a using a MPEG-2 standard, for example, andgenerates an ES (.elementary stream).

The video signal includes GOPs and one GOP has a plurality of frames(pictures). The GOP may include I picture (Intra Picture), P picture(Predictive Picture) and B picture (Bidirectionally Predictive Picture).“IBBPBBPBBPBBPBB” can form one GOP when the GOP comprises 15 frames, forexample. In addition, here, “IBB”, “PBB”, etc. mean sequentialcombinations of “I picture, B picture and B picture”, “P picture, Bpicture and B picture”, etc.

As for I picture, a picture is encoded by a compression encoding in theframe (picture). This compression encoding can use DCT (discrete cosinetransformation) which uses 8×8 pixels as one unit. I picture correspondsto a first video data encoded by an intra-frame encoding.

As for P picture, a picture is encoded by a prediction encoding in aninter-frame (time-axis) forward direction other than the compressionencoding in the frame. As for B picture, a picture is encoded by theprediction coding in the inter-frame (time-axis) forward direction andan opposite direction (both directions) other than the compressionencoding in the frame. P picture and B picture correspond to a secondvideo data encoded by the intra-frame prediction encoding.

The medium control unit 113 controls record of the video data and theaudio data on the recording medium 114 and read-out of the video dataand the audio data from the recording medium 114. The medium controlunit 113 writes the video data and the audio data outputted from theencoding unit 112 on the recording medium 114. Further, the mediumcontrol unit 113 reads the video data and the audio data from therecording medium 114 at a speed corresponding to the playback speed.

The recording medium 114 is a medium on which the information isrecorded and from which the information is read-out. The recordingmedium 114 is a magnetic tape, an optical disc (DVD (Digital VersatileDisk) etc.) and a memory card (SD card etc.), for example.

The video extraction unit 122 a extracts a video frame data from thevideo signal corresponding to the playback speed. The video extractionunit 122 a corresponds to a first extraction unit that extracts thefirst video frame data from the video signal at a first rate.

The audio extraction unit 122 b extracts an audio frame data from theaudio signal corresponding to the playback speed. The audio extractionunit 122 b corresponds to the second extraction unit that extracts theaudio frame data from the audio signal at the second rate.

The video decoding unit 123 a decodes the video frame data extracted bythe video extraction unit 122 a, and outputs the decoded video data as avideo signal. The video decoding unit 123 a functions as an videoplayback unit that plays back the extracted first video frame data thenumber of times which is determined by the main control unit 131.

The audio decoding unit 123 b decodes the audio frame data extracted bythe audio extraction unit 122 b and outputs the decoded audio data as anaudio signal. The audio decoding unit 123 b functions as an audioplayback unit that plays back the extracted audio data.

The video output unit 124 a is a display device which displays a videobased on the video signal decoded by the video decoding unit 123 a. Thevideo output unit 124 a is a liquid crystal display, a plasma display, acathode ray tube, for example.

The audio output unit 124 b is a device which outputs sound based on theaudio signal decoded by the audio decoding unit 123 b. The audio outputunit 124 b is a loudspeaker, a headphone, for example.

The operation input unit 133 is an input device with which a user caninput the information (for example, the playback speed). The operationinput unit 133 is a keyboard, for example.

The main control unit 131 is a control device which controls the videoand audio recording and playback apparatus 10 whole. The main controlunit 131 functions as a deciding unit which determines the first rate atwhich the first video frame data is extracted from the video signal, thesecond rate at which the audio frame data is extracted from the audiosignal, and the number of times which the extracted first video framedata is played back, corresponding to the playback speed. In addition,the main control unit 131 can use a below-mentioned extraction andplayback condition table T for this determination.

The storage unit 132 is a memory or a hard disk drive which memorizesdata, and the storage unit 132 memorizes the extraction and playbackcondition table T. FIG. 2 is a schematic diagram showing an example ofthe extraction and playback condition table T. The extraction andplayback condition table T shows a relation of the playback speed, theextraction rate of the video frame data, the number of times of theplayback of the video frame data, the extraction rate of the audio framedata and the number of times of the playback of the audio frame data.

Next, the playback of the video and the audio is explained.

(1) Extraction and Playback of the Video Frame Data

The playback speed is set ton times as much speed as the standard speed(n>1, high-speed playback) (hereinafter it is described as n× speed),and the number of times of the playback is set to m. Only I picture isextracted in the extraction of the video frame data. Since one GOPincludes 15 frames, n and m are decided so that the extraction rate1/(n×m) of the video frame data may become 1/15. In the video signal,one frame, i.e., I picture, is extracted from one GOP (15 frames). ThisI picture is played back m times. In this case, as mentioned above, themedium control unit 113 reads the video data from the recording medium114 in accordance with the playback speed. The video extraction unit 122a extracts each one I picture from each one GOP (15 frames) of the videosignal. The video decoder 123 a plays back each I picture 5 times at thetime of 3× speed, plays back each I picture 3 times at the time of 5×speed, and plays back each I picture once at the time of 15× speed. OnlyI picture is extracted and is played back repeatedly, so that a simpleand assured playback processing at a high-speed is attained andvisibility of the played back video is improved.

(2) Extraction and Playback of the Audio Frame Data

The method of extraction of the audio frame data differs from the methodof extraction of the video frame data. Since the voice data is easy todecode compared with the video data, even if the audio frame other thanthe audio frame corresponding to the video frame to play back is used, ahigh-speed audio playback processing is carried out certainly andeasily. Further, a repetition playback is not carried out, so that theplayed back sound is easy to listen.

The playback speed is set to n× speed (n>1, high-speed playback), andthe number of times of the playback is set to m. Since the audio is notplayed back repeatedly unlike the video, the number of times of theplayback is 1 time (m=1). At n× speed (n>1), one frame data is extractedfrom the (n×m) frames of the audio signal at an extraction rate of1/(n×m). The extracted audio frame data is decoded and played back. Forexample, the audio extraction unit 122 b extracts one audio frame datafrom every three frames at the time of 3× speed, extracts one audioframe data from every five frames at the time of 5× speed, and extractsone audio frame data from every 15 frames at the time of 15× speed(hereinafter, it is called an extraction condition 1). In the case of 3×speed and 5× speed, the amount of information included in the audio tobe played back can be increased by increasing the audio frame to be usedmore than the video frame. Uncomfortable feeling to the sound playedback can be reduced by not playing back repeatedly.

The method of extraction of the audio frame is not restricted to theabove-mentioned example. Seven frame data may be extracted from 21frames at the time of 3× speed, four frame data may be extracted from 20frames at the time of 5× speed, and one frame data may be extracted from15 frames at the time of 15× speed (hereinafter, it is called anextraction condition 2). In this case, in 3× speed and 5× speed, thesound easy to recognize is reproduced by extracting continuous frames.

The extraction condition of the audio frame is fixable to either one ofthe extraction condition 1 or the extraction condition 2. Furthermore,the extraction condition may be changed to the extraction condition 1 orthe extraction condition 2 from another by the input inputted to theoperation input unit 133.

In addition, in the both of the video and the audio, all the frames areextracted and played back at the 1× speed (the standard speed).

(Operation of the Video and Audio Recording and Playback Apparatus 10)

Hereinafter, the operating procedure of the video and audio recordingand playback apparatus 10 is explained. FIG. 3 is a flow chart showingan example of the operating procedure of the video and audio recordingand playback apparatus 10.

(1) Setup of the Playback Speed (Step S11)

The playback speed (n=1, 3, 5, 15) is chosen by the operation input unit133, and the operation input unit 133 receives the selected playbackspeed. The extraction condition of the audio frame data is also chosenand the operation input unit 133 receives it.

(2) Determination of the Extraction Rate of the Data and the Number ofTimes of the Playback (Step S12)

The extraction rate and the number of times of the playback of the dataare determined based on the playback speed. The main control unit 131determines the extraction rate and the number of times of the playbackof the data with reference to the extraction and playback conditiontable T.

(3) Extraction of the Video Data and the Audio Data (Step S13)

The video data and the audio data are extracted based on the extractionrates which were determined. The video extraction unit 122 a extractsthe video frame data corresponding to the playback speed from the videosignal, and the audio extraction unit 122 b extracts the audio framedata corresponding to the playback speed from the audio signal.

(4) Playback of the Video Data and the Audio Data (Step S14)

The video data and the audio data are played back. The video decodingunit 123 a decodes the extracted video frame data and outputs decodedvideo data as the video signal. The audio decoding unit 123 b decodesthe extracted audio frame data and outputs the decoded audio data as theaudio signal. At this time, the video decoding unit 123 a decodes theextracted video frame data the determined number of times continuouslyrepeatedly based on the determined number of the times of playback. Onthe other hand, the audio decoding unit 123 b decodes the audio framedata once. As a result, the video frame data and the audio frame data of1/n of the original frame number are played back, and thereby the videoand the audio are played back at n× speed.

According to the embodiment, the video and audio playback apparatus andthe video and audio playback method which generate the video and theaudio in accordance with the each characteristic at the time of thehigh-speed playback can be provided.

In the above-mentioned embodiment, the video decoder 123 a plays backthe frame which the video extraction unit 122 a outputs, repeatedlymultiple times. Instead of this, the video extraction unit 122 a mayoutput the same frame repeatedly multiple times and the video decoder123 a may play back the video data which the video extraction unit 122 aoutputs.

In the above-mentioned embodiment, the medium control unit 113 read outthe video data and the audio data from the recording medium 114, thevideo extraction unit 122 a extracts the predetermined video data fromthe video data, and the audio extraction unit 122 b extracts thepredetermined audio data from the audio data. However, a video and audioseparation unit 121 which separates the video and audio data read outinto the video data and the audio data may be installed as shown in FIG.4, depending on the data format of the video and audio data recorded onthe recording medium 114.

The above-mentioned embodiment uses the audio signal which was encodedand compressed. On the other hand, it is also possible to use anuncompressed audio signal. For example, in predetermined frame numbers(5 frames, for example), if the audio signal synchronizes with the videosignal, the audio signal can be applied to the invention regardless ofthe existence of the compression of the audio signal. For example, acombination of an encoded and compressed video signal and anuncompressed audio signal can be used.

In the above embodiment, the video and audio recording and playbackapparatus which includes the video input unit 111 a, the audio inputunit 111 b and the encoding unit 112 is explained. However, the videoand audio playback apparatus of the present invention may be anapparatus without the video input unit 111 a, the audio input unit 111 band the encoding unit 112 only for playback.

Other embodiments or modifications of the present invention will beapparent to those skilled in the art from consideration of thespecification and practice of the invention disclosed herein. It isintended that the specification and example embodiments be considered asexemplary only, with a true scope and spirit of the invention beingindicated by the following.

1. A video and audio playback apparatus for playing back a video andaudio data having a first video data encoded by an intra-frame encoding,a second video data encoded by an inter-frame prediction encoding and anaudio data corresponding to a video frame of the first video data or thesecond video data, the apparatus comprising: an input unit configured toreceive a playback speed; a deciding unit to determine a first rate atwhich the first video data is extracted from the video and audio data, asecond rate at which the audio data is extracted from the video andaudio data, and a number of times which the first video data extractedis played back, in accordance with the playback speed received by theinput unit; a first extraction unit configured to extract the firstvideo data from the video and audio data at the first rate decided bythe deciding unit; a second extraction unit configured to extract theaudio data from the video and audio data at the second rate decided bythe deciding unit; a video playback unit configured to playback thefirst video data extracted by the first extraction unit the number oftimes determined by the deciding unit; and an audio playback unitconfigured to playback the audio data extracted by the second extractionunit.
 2. The video and audio playback apparatus according to claim 1,wherein the second extraction unit extracts the audio data of aplurality of continuous frames.
 3. The video and audio playbackapparatus according to claim 1, wherein the first video data is Ipicture of MPEG, and the second video data is P picture of the MPEG or Bpicture of the MPEG.
 4. The video and audio playback apparatus accordingto claim 1, wherein the first extraction unit outputs the first videodata extracted, and the video playback unit repeatedly the number oftimes determined by the deciding unit plays back the first video dataoutputted from the first extraction unit.
 5. The video and audioplayback apparatus according to claim 1, wherein the first extractionunit repeatedly the number of times determined by the deciding unitoutputs the first video data extracted, and the video playback unitplays back the first video data outputted repeatedly from the extractionunit.
 6. A video and audio data playback method for playing a firstvideo data encoded by an intra-frame encoding, a second video dataencoded by an inter-frame prediction encoding and an audio datacorresponding to a video frame of the first video data or the secondvideo frame, the method comprising: a receiving step to receive aplayback speed, a deciding step to decide a first rate at which thefirst video data is extracted from the video and audio data, a secondrate at which the audio data is extracted from the video and audio data,and a number of times which the first video data extracted is playedback, in accordance with the playback speed received by the receivingstep; a first extracting step to extract the first video data from thevideo and audio data at the first rate decided by the deciding step; asecond extracting step to extract the audio data from the video andaudio data at the second rate decided by the deciding step; a firstplaying back step to play back the first video data extracted by thefirst extracting step the number of times determined by the decidingstep; and a second playing back step to play back the audio dataextracted by the second extracting step.
 7. A video and audio playbackapparatus, comprising: a recording medium configured to record a videodata having a plurality of video frames including a first video dataencoded by an intra-frame encoding and a second video data encoded by aninter-frame prediction encoding, and an audio data having an audio framedata corresponding to the video frames; a storage unit configured torecord a video frame extraction rate at which the first video frame datais extracted from the video data, an audio frame extraction rate atwhich the audio frame data is extracted from the audio data, and anumber of times of a video playback which the first video frame dataextracted is played back, according to a playback speed; an input unitconfigured to receive the playback speed; a deciding unit configured toread the video frame extraction rate, the audio frame extraction rate,and the number of times of the video playback, in accordance with theplayback speed received by the input unit with reference to the storagemedium, and to decide a first rate at which the first video frame datais extracted from the video, a second rate at which the audio frame datais extracted from the audio data, and the number of times which thefirst video data extracted is played back; a medium control unitconfigured to read the video data and the audio data from the recordingmedium in accordance with the playback speed received by the input unit;a first extraction unit configured to extract the first video frame dataat the first rate from the video data; a second extraction unitconfigured to extract the audio frame data at the second rate from theaudio data; a video playback unit configured to play back the number oftimes the first video frame data extracted by the first extractionunits; and an audio playback unit configured to play back the audioframe data extracted by the second extraction unit.